Density Functional Theory Study for Azo Dye Doped with (Si, Ti, S, Zn, Al, Cu, Ni) Atoms as A sensitizer of Dye-Sensitized Solar Cells (DSSCs)

Abstract

The possibility of nanostructures of azo dye-doped with (Si, Ti, S, Zn, Al, Cu, Ni) atoms as a sensitizer of DSSC is investigated. The density functional theory DFT with B3LYP/6-31G is used to get the geometrical optimizations and electronic properties of nanostructures. The feasibility of the nanostructures as the sensitizer of DSSC is studied by the lowest unoccupied molecular orbital LUMO and high occupied molecular orbital HOMO of the nanostructures and the  electrolyte, and TiO2 electrode, the charge spatial separation, the energy gap. Also, the time-dependent DFT (TD-DFT) is used to investigate the optical absorptions and light-harvesting efficiency of the optimized nanostructures. The results show that all the nanostructures except azo-Al have HOMO and LUMO that satisfy the condition of sensitizers. However, only three of the eight considered nanostructures exhibit charge spatial separation. The most azo-doped nanostructures improved absorptions in the visible region. The azo doped with the sulfur atom azo-S is recognized as the most promising applicant sensitizer of DSSCs which is the most suitable LUMO and HOMO. It is characterized by charge spatial separation, low recombination rate, and good light-harvesting efficiency.